Unloader



R. L. DILLS Feb. 16, 1954 UNLOADER Filed March 4, 1952 Inventor: Ragmoncl l Dills,

His AttOTT16Q- Patented Feb. 16,1954

UNLOADER Raymond L. Dills, Erie, Pa., assignor to General Electric Company, a corporation of New York Application March 4, 1952, Serial No. 274,813

My invention relates to refrigeration apparatus and pertains more particularly to refrigerating units.

One form of refrigerating unit comprises a hermetically sealed case housing a rotary compressor and a motor for driving the compressor. The compressor includes an annulus and a rotor operating eccentrioally in the annulus. The annulus is formed with a radial slot; and, a blade positioned slidably in the slot follows the rotor resiliently and thereby divides the compressor into high and low pressure sides. The eccentric operation of the rotor in the annulus causes a mixture of vaporous refrigerant and oil to be drawn from a refrigerating system into the annulus through an intake port on one side of and adjacent the blade. The mixture is compressed by the eccentrio operation of the rotor in the annulus and expelled out an exhaust port on the other side of and adjacent the blade.

It is desirable from the standpoints of economy in cost of construction, operation and space to employ as small and eiiicient a motor as possible for driving the compressor. Such a motor, however, has a low starting torque. Therefore, it is essential to the satisfactory operation of the unit to provide means whereby the motor is permitted to develop maximum torque when starting before the compressor is loaded.

Accordingly, it is the primary object of my invention to provide in a refrigerating unit including a rotary compressor and a motor for driving the compressor, an improved arrangement whereby the motor is permitted to develop maximum torque when starting before the compressor is loaded.

It is another object of my invention to provide in a refrigerating unit including a rotary compressor and a motor for driving the compressor, improved means whereby the compressor is maintained unloaded when the motor is idle or developing less than maximum torque.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out th objects of my invention I provide a refrigerating unit including a compressor and a motor driving the compressor. A blade is biased by a first spring for following a rotor operating eccentrically in the compressor. A piston is spring urged for overcoming the first spring to lift the blade from the rotor. Oil pumping means operated by the motor effects oil pressures proportionate to the torque developed by the motor. The oil is directed against the piston and 5 Claims. (Cl. 230-138) when the motor is developing maximum torque the pressure of the oil is sufficient for restraining the piston from lifting the blade from the rotor.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is a fragmentary sectional view of a refrigerating unit incorporating an embodiment of my invention; Fig. 2 is a fragmentary sectional view taken along the lin 2-2 in Fig. 1 and looking in the direction of the arrows; and Fig. 3 is a fragmentary sectional view illustrating the blade lifted from the rotor.

In Fig. 1, I have shown the lower part of a refrigerating unit I lhe unit I includes a hermetically sealed case 2. The lower end of the case 2 constitutes an oil sump indicated by 3. Housed in th lower part of the case 2 is a rotary compressor generally designated 4; and housed in the upper part of the case is a motor 5 (partly shown) for driving the compressor 4.

Formed integrally with the drive shaft of the motor 5 is a vertical crankshaft 6. The upper and lower portions of the crankshaft 6 are journaled in upper and lower frames I and la, re spectively. The upper and lower frames are spaced apart by an annulus 8 located concentrically with respect to the crankshaft 6. Formed on the crankshaft 6 in the same plane as the annulus 8 is an eccentric 9. Carried rotatably on the eccentric 9 is a rotor l0; and when the crank shaft 6 rotates the rotor I0 operates eccentrically in th annulus 8.

As better seen in Fig. 2, a radial slot II is provided in the annulus 8. Formed in the annulus 8 on one side of and adjacent the radial slot II is an intake port 12. Connected to the intake port I2 is a suction line l3 of a refrigerating system (not shown). Formed in the annulus 8 on the other side of and also adjacent the slot H is an exhaust port Hi. The exhaust port I4 connects with a muffler chamber l5 formed by a recess I6 in the under side of th lower frame 1 and a cover plate i? secured to the lower frame by a screw 18.

Positionedslidably in the radial slot ill is a blade 19. By means to be described in detail hereinafter, the blade I9 is biased for following the rotor H) thereby to divide the compressor into high and low pressure sides. In this arrangement, eccentric operation of the rotor 10 in the annulus 8 causes a mixture of vaporous refrigerant and oil to be drawn into the annulus from the refrigerating system through the suction line l3 and the intake port l2, compressed and expelled through the exhaust port 14 into the muffler chamber l5.

.The mufiler chamber 15 effectively dampens exhaust noises and minimizes transmission of I sound to the case 2. From the muflier chamber upper frame I.

'erating plunger, 38 connected to the piston 31 passes slidingly and closely through a the 'Z-shaped. arm 30.

'centric 9.

IS, the compressed mixture of gas and oil is conducted by a tube 20 to an annular chamber 2| formed between the upper frame I and the case 2. The annular chamber 2| assists the muffler chamber |5 in damping the exhaust noises. From the annular chamber 2 I, the compressedmixture passes through a passage 22 formed in the upper frame 1 into a trough 23 also formed in the upper frame. In the trough 23, the gas and oil separate. The gas is drawn out of the case 2 by means not shown. The oil collects in the bottom of the trough 23 as a reserve indicated by 24. Some separation of gas and oil also takes place in the annular chamber 2|. The separated gas from the annular chamber passes into the trough 23 through the passage 22. A passage 25 permits separated oil to drain from the annular chamber 2| into the bottom of the trough 23 wherein it is added to the reserve 24. A passage 25 determines the maximum level of the reserve 24 and all oil in excess thereof is drained through the passage 26 into the sump 3 to replenish another reserve 2'! therein. Still another passage 28 in the upper frame I conducts oil from the reserve 24 in the trough 23 to the radial slot H for maintaining an oil seal about the blade I9 therein.

Secured to or formed integrally with the outer end of the blade I9 is an upright portion 29 of a substantially Z-shapedarm 38. Positioned in a spring seat 3| in the upright portion 29 is one end of a compression spring 32. The other end of the spring 32 is disposed in a spring seat 33 formed in a bracket 34 suitably secured to the The. spring 32 biases the blade l3 inwardly for engaging and following the rotor l8 as it rotates eccentrically in the annulus 8.

Formed in thelowerframe 1a is a horizontal cylinder 35, the outer end of which is closed by a cap 36 threaded thereinto. Provided for opin the cylinder 35 is a piston 31. A

bore 39 in the cap 38 and is associated with a pendent portion 40 of A compression spring 4| is located in the cylinder 35 between the inner end thereof and the piston 31. The spring 4| is 'strongerthan the spring 32 and biases the piston 31 and plunger38 outwardly for causing the plunger 38 to engage the pendent portion 43 of the arm 30, overcome the weaker spring 32 and 'lift the blade |9 out of following engagement with the rotor It! in the manner shown in Fig. 3. When the blade i9 is so lifted from the rotor, the pressure between the high and low pressure sides of the compressor is equalized and the compressor is unloaded or rendered incapable of doing any work of compression.

Formed in the center of the cover plate I1 is an oil inlet hole 42. A diametrical groove 43 formed in the lower end of the crankshaft 6 communicates with a spiral groove 44 formed in the lower portion of the crankshaft 6. The diametrical groove 43 draws oil from the reserve 21 in the sump 3 through the oil inlet hole 42 and forces it into the spiral groove 44. The spiral groove 44 conveys the oil to the underside of the eccentric 9. 'A vertical groove 45 in the eccentric '9 conducts the oil from the under side of the cocentric to the upper side thereof. Another spiral groove 46 conducts the oil upwardly from the ec- Communicating with the spiral groove 46 is an internal annular groove 41 formed in the upper frame 1. The upper end turn of the spiral groove 45 extends as a restriction 48 be- ;yond the upper edge of the upper frame I. When the crankshaft 6 is rotated by the motor, oil is pumped up from the reserve 21 by the diametrical groove 43 and the spiral grooves 44 and 46. The restriction 48 in the upper end turn of the spiral groove 45 causes pressure to build up in the spiral grooves 44 and 46 and the annular groove 41. The oil pressure is proportionate to the speed of rotation of the crankshaft or the torque being developed by the motor 5 driving the crankshaft. The oil pressure builds up from nothing when the unit is idle to a maximum when the motor 5 is developing maximum torque. The maximum oil pressure is determined bythe size of the restriction 48 and can be varied by varying the restriction.

A passage 49 in the upper frame I communicates with the annular groove 41. The passage 43 is formed by a vertical bore 58 and a connecting horizontal bore 5|. The outer end of the vertical bore 50 is closed by a plug 52 threaded thereinto. A tube 53 connects the outer end of the horizontal bore 5| with the cylinder 35 at a point between the head of the piston 31 and the cylinder cap 36. By this arrangement oil under pressure is conducted from the annular groove 41 to the cylinder 35 for acting on the piston 31 against the force of the spring 4|. 1

The strength of the stronger spring 4| is such that it will be overcome and compressed .by no less than the maximum oil pressure or the oil pressure attained when the motor of the unit is developing maximum torque. Therefore,- it will be seen that when the unit is starting and until the motor 5 has developed maximum torque the stronger spring 4| will be effective for causing the plunger 38 to lift the blade I3 from the rotor ill against the tension of the weaker spring 32 in the manner shown in Fig. 3. Thus the motor 5 is permitted to develop maximum torque when starting before the compressor 4 is loaded. When the motor 5 has developed maximum torque, the oil pressure acting on the piston 31 is suflicient to compress the stronger spring 4| and restrain the plunger 38 from lifting the blade H! in .the manner shown in Fig. l. Restraint of the plunger 38 in the described manner permits the weaker spring 32 to cause the blade l9 to follow the 'rotor H1 and thereby permit loading of the compressor and normal operation of the unit.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular form shown and described and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerating unit, a rotary compressor, a motor driving said compressor, said compressor including an annulus having a radial slot, a rotor operating eccentrically in said annulus, a blade slidably positioned in said radial slot, a first suresides of said compressor for unloading said compressor, oil pumping means operated by said motor and effecting oil pressures proportionate to the torque developed by said motor, and means conducting oil from said oil pumping means to said cylinder between said piston and said arm, said second spring being overcome and said plunger being restrained from lifting said blade from said rotor by the pressure of oil on said piston when said motor is developing maximum torque thereby to permit loading of said compressor.

2. In a refrigerating unit, an oil sump, motor,

a rotary compressor including an annulus having a radial slot, a crankshaft driven by said motor, a rotor carried on said crankshaft and operating eccentrically in said annulus, a blade slidably positioned in said radial slot, a first spring biasing said blade for following said rotor thereby to divide said compressor into high and low pressure sides, an arm formed integrally with said blade, a cylinder, 2. piston for operating in said cylinder, a plunger connected to said piston for engaging said arm, a second spring stronger than said first spring biasing said piston for causing said plunger to engage said arm and lift said blade from said rotor thereby to equalize pressure between said high and low pressure 1? sides of said compressor for unloading said compressor, a spiral groove formed in said crankshaft, said spiral groove pumping oil from said oil sump and eifecting oil pressures proportionate to the torque developed by said motor, and means conducting oil from said spiral groove to said cylinder between said piston and said arm, second spring being overcome and said plunger being restrained from lifting said blade from said rotor by the pressure of oil on said piston when said motor is developing maximum torque thereby to permit loading of said compressor.

3. In a refrigerating unit, an oil sump, a motor, a rotary compressor including a frame, an annulus having a radial slot, a crankshaft journaled in said frame and driven by said motor, a rotor carried on said crankshaft and operating eccentrically in said annulus, a blade slidably positioned in said radial slot, a first spring biasing said blade for following said rotor thereby to divide said compressor into high and low pressure sides, an arm formed integrally with said blade, a cylinder, a piston for operating in said cylinder, a plunger connected to said piston for engaging said arm, a second spring stronger than said first spring biasing said piston for causing said plunger to engage said arm and lift said blade from said rotor thereby to equalize pressure between said high and low pressure sides of said compressor for unloading said compressor, a spiral groove formed in said crankshaft, an internal annular groove formed in said frame communicating with said spiral groove, said spiral groove pumping oil from said oil sump to said annular groove and effecting oil pressures in said annular groove proportionate to the torque developed by said motor, and means conducting oil from said annular groove to said cylinder between said piston and said arm, said second spring being overcome and said plunger being restrained from lifting said blade from said rotor by the pressure of oil on said piston when said motor is developing maximum torque thereby to permit loading of said compressor.

4. In a refrigerating unit, an oil sump, a motor, a rotary compressor including a frame, an annulus having a radial slot, a crankshaft driven by said motor and having a portion thereof journaled in said frame, a rotor carried on said crankshaft and operating eccentrically in said annulus, a blade slidably positioned in said radial slot, a first spring biasing said blade for following said rotor thereby to divide said compressor into high and low pressure sides, an arm formed integrally with said blade, a cylinder, a piston for operating in said cylinder, a plunger connected to said piston for engaging said blade, 2. second spring stronger than said first spring biasing said piston for causing said plunger to engage said arm and lift said blade from said rotor thereby to equalize pressure between said high and low pressure sides of said compressor for unloading said compressor, a spiral groove formed on the portion of said crankshaft journaled in said frame, said spiral groove pumping oil from said oil sump, the upper end turn of said spiral groove extending restrictedly beyond said frame and affording a build-up of pressure in said spiral groove, and means conducting oil from said spiral groove to said cylinder between said piston and said arm, said second spring being overcome and said plunger being restrained from lifting said blade from said rotor by the pressure of oil on said piston when said motor is developing maximum torque thereby to permit loading of said compressor.

5. In a refrigerating unit, an oil sump, a mo tor, a rotary compressor including a frame, an annulus having a radial slot, at crankshaft driven by said motor and having a portion thereof journaled in said frame, a rotor carried on said crankshaft and operating eccentrically in said annulus, a blade slidably positioned in said radial slot, a first spring biasing said blade for following said rotor thereby to divide said compressor into high and low pressure sides, an arm formed integrally with said blade, a cylinder, a piston for operating in said cylinder, a plunger connected to said piston for engaging said arm, a second spring stronger than said first spring biasing said piston for causing said plunger to engage said arm and lift said blade from said rotor thereby to equalize pressure between said high and low pressure sides of said compressor for unloading said compressor, a spiral groove formed on the portion of said crankshaft journaled in said frame, a diametrical groove formed in the lower end of said crankshaft and communicating with said spiral groove, said diametrical groove forcing oil eentrifugally from said sump into said spiral groove, an internal annular groove formed in said frame communicating with said spiral groove, the upper end turn of said spiral groove extending restrictedly beyond said frame and affording a build-up of pressure in said spiral groove and said annular groove proportionate to the torque developed by said motor, and means conducting oil from said annular groove to said cylinder between said piston and said arm, said second spring being overcome and said plunger being restrained from lifting said blade from said rotor by the pressure of oil on said piston when said motor is developing maximum torque thereby to permit loading of said compressor.

RAYMOND L. DILLS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,884,702 Hubacker Oct. 25, 1932 1,922,639 Riesner Aug- 1 1933 2,020,987 Ayres Nov. 12, 1935 2,488,942 Schweller Nov. 22, 1949 

